System and method for multicasting multimedia content

Abstract

A multicast network system utilizes a high speed link, such as a satellite link, to multicast multimedia information from the Internet to a plurality of receivers, such as personal computers Information from selected web sites is organized into “channels” and provided to a multicast network for multicast transmission to the receivers. Updated channel information is also periodically provided. The receivers store the received channel such that a user can access the web page content in the channel at hard disk speed. Preferably, a conditional access system ensures that only authorized receivers receive the channels. The present invention also preferably includes a lower speed two-way connection to the Internet (such as dial up modem) which is used to report usage information and/or subscription information back to the web sites The present invention also provides “seamless” or automatic access to this connection to allow the user to retrieve any information that has not been received and stored. The receiver also manages use of memory space and other applications that may be active on the receiver to ensure that the receipt and processing of the multicast information does not interfere with receiver operation.

1 . An apparatus that transmits content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the system comprising: 
 means for assigning one or more multicast addresses to each channel;    means for scheduling the assembling of a channel's content;    means for assembling the channel's content,    means for fragmenting the channel's content into packets, wherein each packet is addressed with one of the channel's multicast addresses; and    means for multicasting the packets.    
     
     
         2  The apparatus of  claim 1 , wherein the means for multicasting the packets includes means for transmitting the packets to a multicast receiver of a multicast network.  
     
     
         3 . The apparatus of  claim 1 , further comprising means for encrypting a subset of a channel's packets prior to multicasting, wherein the encryption means encrypts either all or a part of the packet and wherein each channel's packets are encrypted with a set of encryption keys which are unique to that channel  
     
     
         4  The apparatus of  claim 3 , further comprising. 
 means for receiving requests from a receiver of the multicast for access to a channel's packets,  
 means for mapping the requested channel to the multicast addresses that carry the channel's packets, and  
 means for requesting authorization for the receiver to access the requested channel's packets.  
 
     
     
         5 . The apparatus of  claim 4 , further comprising means for authenticating the requests to ensure that the requests originated from the receiver for which access is being requested.  
     
     
         6  The apparatus of  claim 2 , wherein the multicast network is a geosynchronous satellite digital TV broadcast system.  
     
     
         7  The apparatus of  claim 1 , wherein the multicast network is a one-way cable TV network.  
     
     
         8  The apparatus of  claim 1 , wherein the multicast network is a digital video broadcast (DVB) network.  
     
     
         9 . The apparatus of  claim 1 , wherein the packets are multicast to a plurality of receivers  
     
     
         10 . The apparatus of  claim 9 , wherein a channel's content includes indexing information which allows URL data items contained within the channel's content to be quickly looked up by the receiver which receives the channel's content.  
     
     
         11 . The apparatus of  claim 10 , wherein the channel's content further includes a data structure containing each domain name present in the URLs of the URL data items within the channel's content.  
     
     
         12  The apparatus of  claim 9 , further comprising a conditional access system for controlling each receiver's access to packets, wherein each receiver can only access packets which contain multicast addresses which the conditional access system has authorized the receiver to access  
     
     
         13 . The apparatus of  claim 12 , wherein the means for multicasting the packets is a geosynchronous satellite digital TV broadcast earth station.  
     
     
         14 . The apparatus of  claim 12 , further comprising: 
 means for receiving requests from the receivers to obtain access to a channel's packets,    means for mapping the requested channel to the multicast addresses that carry the channel's packets, and    means for authorizing the receivers' access to a channel's packets in response to the receivers' request for access.    
     
     
         15 . The apparatus of  claim 13 , wherein a channel's content includes indexing information which allows URL data items contained within the channel's content to be quickly looked up by the receiver which receives the channel's content, the system further comprising. 
 means for scheduling a configurable number of retransmissions of the channel's previously assembled content;    means for fragmenting and multicasting the channel's content according to the schedule; and    means for specifying the transmission rate of the channel's content, wherein the packets containing the channel's content are multicast at the specified rate.    
     
     
         16 . The apparatus of  claim 13 , further comprising means for compressing a subset of the URL data items, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items.  
     
     
         17 . The apparatus of  claim 16 , wherein the URL data items are compressed with a lossless data compression algorithm  
     
     
         18 . The apparatus of  claim 1 , further comprising: 
 means for scheduling a configurable number of retransmissions of a channel's previously assembled content, and    means for fragmenting and multicasting the channel's content according to the schedule.    
     
     
         19 . The apparatus of  claim 18 , further comprising means for specifying a transmission rate of a channel's content, wherein the packets containing the channel's content are multicast at the specified rate.  
     
     
         20 . The apparatus of  claim 19 , further comprising: 
 means for assigning one or more multicast addresses to an announcement packet, wherein the announcement packet includes an announcement of an upcoming transmission of a channel's content; and    means for multicasting the announcement packet prior to the multicast of the packets containing the channel's content.    
     
     
         21 . The apparatus of  claim 19 , wherein the channel's content includes a data structure containing each domain name present in the URLs of the URL data items within the channel's content.  
     
     
         22 . The apparatus of  claim 19 , wherein the packets are multicast to a plurality of receivers and wherein a channel's content includes indexing information which allows URL data items contained within the channel's content to be quickly looked up by the receiver which receives the channel's content.  
     
     
         23 . The apparatus of  claim 22 , wherein the channel's content further includes a data structure containing each domain name present in the URLs of the URL data items within the channel's content.  
     
     
         24 . The apparatus of  claim 1 , wherein a channel's content includes a data structure containing each domain name present in the URLs of the URL data items within the channel's content.  
     
     
         25 . The apparatus of  claim 1 , wherein the means for assembling the channel's content further comprises: 
 means for assembling a base package of the channel's content, wherein the base package contains each URL data item in the channel; and    means for assembling a delta package of the channel's content, wherein the delta package contains URL data items which have changed or are new since the previous assembling of the base package    
     
     
         26 . An apparatus that transmits content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the apparatus comprising means for scheduling the assembling of a channel's content; 
 means for assembling the channel's content,    means for compressing a subset of the URL data items, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items;    means for fragmenting the channel's content into packets, and    means for multicasting the packets    
     
     
         27 . The apparatus of  claim 26 , wherein the URL data items are compressed with a lossless data compression algorithm  
     
     
         28 . The apparatus of  claim 26 , wherein the means for assembling the channel's content further comprises: 
 means for assembling a base package of the channel's content, wherein the base package contains each URL data item in the channel; and    means for assembling a delta package of the channel's content, wherein the delta package contains URL data items which have changed or are new since the previous assembling of the base package    
     
     
         29  The apparatus of  claim 28 , wherein the means for scheduling the assembling of the channel's content comprises means for scheduling the assembling of the base package and means for scheduling the assembling of the delta package.  
     
     
         30 . The apparatus of  claim 28 , further comprising means for difference compressing a subset of the URL data items in a channel's content which is present in both the delta package and the previous base package.  
     
     
         31  The apparatus of  claim 30 , wherein the difference compression means further comprises 
 means for dividing a URL data item in the delta package into sections, and  
 for each section, means for placing into a compressed version of the URL data item, one of a reference to where that section can be found in the base package, or the section of URL data item from the delta package.  
 
     
     
         32 . The apparatus of  claim 28 , further comprising means for assembling a second delta package which contains a subject of the URL data items which have changed or are new since the assembling of the previous delta package.  
     
     
         33 . The apparatus of  claim 26 , further comprising means for encrypting a subset of a channel's packets prior to transmission, wherein the encryption means encrypts either all or part of the packet and wherein each channel's packets are encrypted with a set of encryption keys which are unique to that channel.  
     
     
         34 . An apparatus that transmits content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the apparatus comprising: 
 means for assembling a base package of a channel's content, wherein the base package contains each URL data item in the channel;    means for fragmenting the base package into packets;    means for multicasting the base package packets to a plurality of receivers,    means for assembling a delta package of a channel's content, wherein the delta package contains URL data items which have changed or are new since the previous assembling of the base package;    means for fragmenting the delta package into packets; and    means for multicasting the delta package packets to the plurality of receivers.    
     
     
         35 . The apparatus of  claim 34 , wherein some of the receivers comprise a personal computer.  
     
     
         36 . The system of  claim 34 , wherein some of the receivers comprise a set top box.  
     
     
         37  The apparatus of  claim 34 , further comprising means for scheduling the assembling of base packages and delta packages, wherein the base packages and delta packages are assembled according to the schedule.  
     
     
         38 . The apparatus of  claim 34 , further comprising means for scheduling the multicast transmission of base package packets and for scheduling subsequent periodic multicast transmission of delta package packets, wherein the base package packets and delta package packets are multicast according to the schedule  
     
     
         39 . The apparatus of  claim 38 , wherein base package packets are scheduled for transmission at a time when the receiver is not likely to be in use for other applications.  
     
     
         40 . The apparatus of  claim 39 , wherein the base package packets are scheduled for transmission late at night or early in the morning  
     
     
         41 . The apparatus of  claim 34 , further comprising means for compressing a subset of the URL data items in the base and delta packages, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items.  
     
     
         42 . The apparatus of  claim 41 , wherein the URL data items are compressed with a lossless data compression algorithm.  
     
     
         43 . The apparatus of  claim 41 , further comprising means for difference compressing a subset of the URL data items that are present in both in the delta package and the previous base package.  
     
     
         44 . The apparatus of  claim 43 , wherein the difference compression means further comprises 
 means for dividing a URL data item in the delta package into sections; and    for each section, means for placing into a compressed version of the URL data item, one of a reference to where that section can be found in the base package, or the section of URL data item from the delta package.    
     
     
         45 . The apparatus of  claim 44 , further comprising means for compressing a subset of the previously difference compressed URL data item with a lossless data compression algorithm.  
     
     
         46 . The apparatus of  claim 34 , further comprising means for assembling a second delta package which contains URL data items which have changed since the assembling of the previous delta package.  
     
     
         47 . An apparatus that transmits content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the apparatus comprising: 
 means for scheduling the assembling of a channel's content;    means for assembling the channel's content according to the schedule,    means for fragmenting the channel's content into packets,    means for multicasting the packets to a plurality of receivers, wherein each receiver stores the received channel's content in a receiver memory, and    means for receiving usage reports from each receiver, wherein each usage report identifies a subset of URL data items from the stored URL data items that was accessed from the receiver memory.    
     
     
         48 . The apparatus of  claim 47 , further comprising means for organizing the received usage reports by channel.  
     
     
         49 . The apparatus of  claim 47 , wherein each usage report contains information identifying a subset of URL data items delivered to a web browser.  
     
     
         50 . The apparatus of  claim 47 , wherein the usage reports comprise a set of files and wherein the URL data items accessed for each channel is referenced in one set of files  
     
     
         51 . The apparatus of  claim 47 , wherein the usage reports contain information identifying each URL data item, from the stored URL data items, being delivered to a web browser.  
     
     
         52 . The apparatus of  claim 50 , wherein usage reporting is performed on a subset of a channel's URL data items and the files contain a separate record for each time a usage reported URL data item was delivered to a web browser, wherein the record identifies the URL of the URL data item.  
     
     
         53 . The apparatus of  claim 52 , wherein the record identifies when the URL data item was delivered to the web browser.  
     
     
         54  The apparatus of  claim 52 , wherein the record contains a field uniquely identifying the user that accessed the URL data item  
     
     
         55 . The apparatus of  claim 54 , wherein the field uniquely identifying the user does not specific the identity of the user  
     
     
         56 . The apparatus of  claim 54 , wherein the field uniquely identifying the user specifies [he identity of the user.  
     
     
         57 . The apparatus of  claim 47 , wherein a channel's content is assembled from a web server and further comprising means for notifying the web server from which a URL data item was assembled that the URL data item was accessed by a user.  
     
     
         58 . The apparatus of  claim 57 , wherein the web server is notified that the URL data item was accessed by a user by notifying, the web server that the URL data item was delivered to a browser.  
     
     
         59 . The apparatus of  claim 57 , wherein the web server is notified that the URL data item was accessed by initiating an HTTP GET operation for the URL data item  
     
     
         60 . The apparatus of  claim 57 , wherein the web server is notified of multiple accesses of multiple URL data items by initiating an HTTP PUT operation.  
     
     
         61 . The apparatus of  claim 57 , wherein the web server is notified of multiple accesses of multiple URL data items by initiating an HTTP POST operation.  
     
     
         62 . The apparatus of  claim 57 , wherein the web server is notified that the URL data item was accessed by e-mail, and wherein multiple accesses of multiple URL data items is reported in one e-mail.  
     
     
         63 . The apparatus of  claim 47 , further comprising means for compressing a subset of the URL data items; 
 means for compressing a subset of the URL data items, wherein each URL data item is compressed individually independent of other URL data item such that each compressed URL data item can be decompressed without decompressing other URL data items;    
     
     
         64 . A method for multicasting content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the method comprising the steps of. 
 assigning one or multicast addresses to each channel;    scheduling the assembling of each channel's content;    assembling each channel's content according to the schedule;    fragmenting each channel's content into packets, wherein each packet is addressed with one of the channel's multicast addresses, and    transmitting the packets via a multicast network to a plurality of receivers    
     
     
         65 . The method of  claim 64 , further comprising encrypting a subset of a channel's packets prior to transmitting the packets, wherein either all or a part of the packet are encrypted and wherein each channel's packets are encrypted with a set of encryption keys which are unique to that channel  
     
     
         66  The method of  claim 65 , further comprising the steps of 
 receiving requests from the receivers for access to a channel's packets,  
 mapping the requested channel to the multicast addresses that carry the channel's packets; and  
 requesting authorization from the multicast network for the receiver to access the requested channel's packets  
 
     
     
         67  The method of  claim 66 , further comprising the step of authenticating the requests to ensure that the requests originated from the receiver for which access is being requested.  
     
     
         68 . The method of  claim 64 , wherein a channel's content includes indexing information which allows URL data items contained within the channel's content to be quickly looked up by the receiver which receives the channel's content.  
     
     
         69 . The method of  claim 68 , wherein the channel's content further includes a data structure containing each domain name present in the URLs of the URL data items within the channel's content.  
     
     
         70  The method of  claim 68 , wherein a channel's content includes indexing information which allows URL data items contained within the channel's content to be quickly looked up by the receiver which receives the channel's content, the method further comprising the steps of. 
 scheduling a configurable number of retransmissions of the channel's previously assembled content;  
 specifying a transmission rate of the channel's content, and fragmenting and transmitting the channel's content to the receivers  
 according to the schedule at the specified transmission rate.  
 
     
     
         71 . The method of  claim 65 , further comprising the step of compressing a subset of the URL data items, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items.  
     
     
         72 . The method of  claim 71 , wherein the URL data items are compressed with a lossless data compression algorithm.  
     
     
         73 . The method of  claim 64 , further comprising the steps of. 
 scheduling a configurable number of retransmissions of a channel's previously assembled content, and    fragmenting and transmitting the channel's content to the receivers according to the schedule.    
     
     
         74 . The method of  claim 73 , further comprising the step of specifying a transmission rate of a channel's content, wherein the packets containing the channel's content are transmitted at the specified rate.  
     
     
         75 . The method of  claim 73 , further comprising the steps of: 
 assigning one or more multicast addresses to an announcement packet, wherein the announcement packet includes an announcement of an upcoming transmission of a channel's content, and    transmitting the announcement packet to the receivers prior to transmitting the packets containing the channel's content.    
     
     
         76 . The method of  claim 64 , wherein the step of assembling the channel's content further comprises: 
 assembling a base package of the channel's content, wherein the base package contains each URL data item in the channel; and    assembling a delta package of the channel's content, wherein the delta package contains URL data items which have changed or are new since the previous assembling of the base package.    
     
     
         77 . A method for transmitting content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the method comprising the steps of: 
 scheduling the assembling of a channel's content;    assembling the channel's content according to the schedule;    compressing a subset of the URL data items, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items;    fragmenting the channel's content into packets; and    multicasting the packets via a multicast network to a plurality of receivers.    
     
     
         78 . The method of  claim 77 , wherein the URL data items are compressed with a lossless data compression algorithm.  
     
     
         79 . The method of  claim 77 , wherein the step of assembling the channel's content further comprises the steps of: 
 assembling a base package of the channel's content, wherein the base package contains each URL data item in the channel; and    assembling a delta package of the channel's content, wherein the delta package contains URL data items which have changed or are new since the previous assembling of the base package.    
     
     
         80 . The method of  claim 79 , wherein the step of scheduling the assembling of the channel's content comprises scheduling the assembling of the base package and scheduling the assembling the delta package.  
     
     
         81 . The method of  claim 80 , further comprising the step of difference compressing a subset of the URL data items in a channel's content which is present in both the delta package and the previous base package  
     
     
         82 . The method of  claim 81 , wherein the step of difference compressing further comprises the steps of 
 dividing a URL data item in the delta package into sections; and    for each section, placing into a compressed version of the URL data item, one of a reference to where that section of content can be found in the base package, or the section of the URL data item from the delta package.    
     
     
         83 . The method of  claim 82 , wherein the reference to where the section of URL data item can be found in the base package is an offset from a beginning of the URL to a first byte and an offset to a last byte being referenced.  
     
     
         84 . The method of  claim 79 , further comprising the step of assembling a second delta package which contains URL data item which has changed since the assembling of the previous delta package.  
     
     
         85 . The method of  claim 77 , further comprising the step of encrypting a subset of a channel's packets prior to transmission, wherein either all or part of the packet are encrypted and wherein each channel's packets are encrypted with a set of encryption keys which are unique to that channel.  
     
     
         86 . A method for transmitting content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the system comprising. 
 assembling a base package of a channel's content, wherein the base package contains each URL data item in the channel,    fragmenting the base package into packets;    multicasting the base package packets to a plurality of receivers,    assembling a delta package of a channel's content, wherein the delta package contains URL data items which have changed or are new since the previous assembling of the base package;    fragmenting the delta package into packets, and    multicasting the delta package packets to the plurality of receivers    
     
     
         87 . The method of  claim 86 , further comprising the step of scheduling the assembling of base packages and delta packages, wherein the base packages and delta packages are assembled according to the schedule.  
     
     
         88 . The method of  claim 86 , further comprising the step of scheduling the multicast transmission of base package packets and for scheduling subsequent periodic multicast transmission of delta package packets, wherein the base package packets and delta package packets are multicast according to the schedule  
     
     
         89  The method of  claim 88 , where in base package packets are scheduled for transmission at a time when the receiver is not likely to be in use for other applications.  
     
     
         90 . The method of  claim 86 , further comprising the step of compressing a subset of the URL data items in the base and delta packages, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items.  
     
     
         91 . The method of  claim 90 , wherein the URL data items are compressed with a lossless data compression algorithm  
     
     
         92 . The method of  claim 90 , further comprising the step of difference compressing a subset of the URL data items which are present in both in the delta package and the previous base package.  
     
     
         93 . The method of  claim 92 , wherein the step of difference compressing further comprises: 
 dividing a URL data item in the delta package into sections; and    for each section, placing into a compressed version of the URL data item, one of a reference to where that section can be found in the base package, or the section of the URL data item from the delta package.    
     
     
         94  The method of  claim 93 , wherein the reference to where the section of URL data item can be found in the base package is an offset from a beginning of the URL to a first byte and an offset to a last byte being referenced.  
     
     
         95 . The method of  claim 93 , further comprising compressing a subset of the previously difference compressed URL data items with a lossless data compression algorithm  
     
     
         96  The method of  claim 86 , further comprising the step of assembling a second delta package that contains URL data items that have changed since the assembling of the previous delta package  
     
     
         97 . A method for transmitting content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, the method comprising the steps of: 
 scheduling the assembling of a channel's content;    assembling the channel's content according to the schedule;    fragmenting the channel's content into packets,    multicasting the packets to a plurality of receivers, wherein each receiver stores the received channel's content in a receiver memory; and    receiving usage reports from each receiver, wherein each usage report identifies a subset of URL data items from the stored URL data items that was accessed from the receiver memory.    
     
     
         98 . The method of  claim 97 , further comprising the step of organizing the received usage reports by channel.  
     
     
         99 . The method of  claim 97 , wherein each usage report contains information identifying a subset of URL data items delivered to a web browser.  
     
     
         100 . The method of  claim 97 , wherein the usage reports comprise a set of files, and wherein the URL data item accessed for each channel is referenced in one set of files  
     
     
         101  The method of  claim 97 , wherein the usage reports contain information identifying each URL data item, from the stored URL data items, being delivered to a web browser.  
     
     
         102 . The method of  claim 100 , further comprising the step of performing usage reporting on a subset of a channel's URL data items and wherein the files contain a separate record for each time a usage reported URL data item was delivered to the web browser, and wherein the record identifies the URL of the URL data item.  
     
     
         103 . The method of  claim 102 , wherein the record identifies when the URL data item was delivered to the web browser.  
     
     
         104 . The method of  claim 102 , wherein the record contains a field uniquely identifying the user that accessed the URL data item.  
     
     
         105 . The method of  claim 104 , wherein the field uniquely identifying the user does not specify the identity of the user.  
     
     
         106 . The method of  claim 104 , wherein the field uniquely identifying the user specifies the identity of the user.  
     
     
         107 . The method of  claim 97 , wherein a channel's content is assembled from a web server and further comprising the step of notifying the web server from which a URL data item was assembled that the URL data item was accessed by a user.  
     
     
         108 . The method of  claim 107 , wherein the web server is notified that the URL data item was accessed by a user by notifying the web server that the URL data item was delivered to a browser.  
     
     
         109 . The method of  claim 107 , wherein the web server is notified that the URL data item was accessed by initiating an HTTP GET operation for the URL data item.  
     
     
         110  The method of  claim 107 , wherein the web server is notified of multiple accesses of multiple URL data items by initiating an HTTP PUT operation.  
     
     
         111 . The method of  claim 107 , wherein the web server is notified of multiple accesses of multiple URL data items by initiating an HTTP POST operation.  
     
     
         112 . The method of  claim 107 , wherein the web server is notified that the URL data item was accessed by e-mail, and wherein multiple accesses of multiple URL data item is reported in one e-mail.  
     
     
         113 . The method of  claim 97 , further comprising the step of compressing a subset of the URL data items, wherein each URL data item is compressed individually independent of other URL data items such that each compressed URL data item can be decompressed without decompressing other URL data items.  
     
     
         114 . A receiver for receiving from a multicast network content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, and wherein the multicast network transmits the channel's content to the receiver in packets, the receiver comprising 
 means for determining a multicast address used to carry a channel's packets;    means for enabling reception of packets containing a channel's multicast address;    means for receiving the packets containing a channel's multicast address;    means for assembling the received packets into a channel's content;    means for storing the channel's content; and    means for allowing a user to access the stored channel's content.    
     
     
         115 . The receiver of  claim 114 , wherein some of the received packets are wholly or partially encrypted and the receiver further comprises means for decrypting the encrypted packets using a decrypting key unique to the channel.  
     
     
         116 . The receiver of  claim 114 , wherein the receiver is only authorized to receive selected packets  
     
     
         117 . The receiver of  claim 114 , wherein the channel's content is stored in a single file.  
     
     
         118 . The receiver of claim l  14 , wherein the channel's content is stored in a number of files, and wherein the number of files is less than the total number of URL data items in the channel  
     
     
         119 . The receiver of  claim 114 , further comprising means for allowing the user to designate the channels to be received.  
     
     
         120 . The receiver of  claim 119 , further comprising means for only receiving the user designated channels  
     
     
         121 . The receiver of  claim 120 , further comprising means for displaying to the user the set of channels which can be received  
     
     
         122 . The receiver of  claim 121 , further comprising means for receiving an electronic program guide channel, wherein the content of the electronic program guide channel includes channel selection information allowing the user to evaluate which channels the receiver should receive.  
     
     
         123 . The receiver of  claim 122 , further comprising means for receiving updates for the electronic program guide channel.  
     
     
         124 . The receiver of  claim 122 , wherein the channel selection information in the electronic program guide channel includes a schedule for when the content of the channels will be transmitted.  
     
     
         125 . The receiver of  claim 122 , wherein the channel selection information in the electronic program guide channel includes an amount of memory space needed to store the channel's content  
     
     
         126 . The receiver of  claim 114 , further comprising means for determining whether all the packets for a channel have been received.  
     
     
         127 . The receiver of  claim 126 , wherein the multicast network transmits packets to the receiver more than once and further comprising means for determining which packets for a channel were not received and assembling the channel's missing packets from the retransmitted packets.  
     
     
         128  The receiver of  claim 114 , wherein the receiver comprises a personal computer.  
     
     
         129 . The receiver of  claim 114 , wherein the receiver comprises a set top box  
     
     
         130 . The receiver of  claim 1   14 , wherein the receiver is integrated with a digital television.  
     
     
         131  The receiver of  claim 114 , further comprising: 
 means for determining when a URL data item requested to be accessed by the user is not present within the stored channel content,  
 means for notifying the user that the requested URL data item is not present within the stored channel content, and  
 means for allowing the user to access the non-present URL data item via a connection to a TCP/IP network.  
 
     
     
         132 . The receiver of  claim 131 , wherein the TCP/IP network comprises the Internet.  
     
     
         133  The receiver of  claim 131 , further comprising means for soliciting the user whether to access the non-present URL data item via the connection to the TCP/IP network.  
     
     
         134 . The receiver of  claim 132 , wherein the multicast network is a geosynchronous satellite broadcast system and wherein the connection to the Internet is a dial-up modem.  
     
     
         135 . The receiver of  claim 114 , further comprising means for tracking each time the user accesses URL data items in the stored channel content.  
     
     
         136  The receiver of  claim 135 , further comprising means for reporting the tracked user accesses to a web site from which the accessed URL data items were assembled.  
     
     
         137 . The receiver of  claim 114 , wherein the packet receiving means monitors receiver activity and selectively receives packets based on the monitored activity.  
     
     
         138 . The receiver of  claim 114 , further comprising means for soliciting the user to determine when packets should be received and wherein the packet receiving means selectively receives packets based on user preferences  
     
     
         139  A receiver for receiving from a multicast network content organized into channels, wherein a channel's content includes a plurality of URL data items and each URL data item is addressed by a URL, and wherein the multicast network transmits the channel's content to the receiver in packets, the receiver comprising: 
 means for determining a multicast address used to carry a channel's packets;  
 means for enabling reception of packets containing a channel's multicast address;  
 means for receiving the packets containing a channel's multicast address;  
 means for assembling the received packets into a channel's content;  
 means for storing the channel's content;  
 means for allowing a user to access the stored channel's content; and  
 means for individually decompressing each compressed URL data item in the stored channel content at a time when the user accesses the URL data item.  
 
     
     
         140 . The receiver of  claim 139 , wherein the URL data item is decompressed a first time the user access the URL data item and further comprising means for storing the decompressed URL data item  
     
     
         141 . The receiver of  claim 139 , wherein the URL data item is decompressed each time a user access the URL data item.  
     
     
         142  The receiver of  claim 139 , wherein the multicast network transmits a channel's content in base package packets and delta package packets, and the means for assembling the base package packets into a complete base package and assembling the delta package packets into a complete delta package.  
     
     
         143 . The receiver of  claim 142 , wherein the means for storing the channel's content stores the complete base package for the channel and the complete delta package for the channel.  
     
     
         144 . The receiver of  claim 142 , wherein the means for allowing a user to access the stored channel's content provides the user with a URL data item from a delta package when the URL data item is present in a delta package and provides the user a URL data item from a base package when the URL data item is not present in a delta package  
     
     
         145  A receiver in a multicast system, comprising: 
 means for receiving URL data items from a multicast network;  
 means for storing the received URL data items;  
 means for allowing a user to access the stored URL data items; and  
 means for tracking user access to the stored URL data items  
 
     
     
         146 . The receiver of  claim 145 , wherein the URL data items are assembled from a web site and further comprising means for reporting the tracked user access to the web site  
     
     
         147 . The receiver of  claim 145 , wherein the tracking means includes means for counting a number of times the user accesses a subset of the stored URL data items.  
     
     
         148 . The receiver of  claim 145 , further comprising 
 means for determining when a URL data item requested to be accessed by the user is not present within the stored URL data items,    means for notifying the user that the requested URL data item is not present within the stored URL data items, and    means for allowing the user to access the non-present URL data item via a connection to a TCP/IP network.    
     
     
         149 . The receiver of  claim 148 , further comprising means for soliciting the user whether to access the non-present URL data item via the connection to the TCP/IP network.  
     
     
         150 . The receiver of  claim 148 , wherein the multicast network is a geosynchronous satellite broadcast system and wherein the connection to the TCP/IP network is a dial-up modem.  
     
     
         151 . A receiver in a multicast system, comprising. 
 means for monitoring receiver activity; and    means for selectively receiving content from a multicast network, wherein the content is selectively received based on the monitored receiver activity    
     
     
         152 . The receiver of  claim 151 , wherein the monitoring means monitors whether any other applications are currently active on the receiver  
     
     
         153 . The receiver of  claim 151 , wherein the monitoring means monitors utilization of a receiver memory  
     
     
         154 . The receiver of  claim 151 , wherein the monitoring means monitors user activity on an input device of the receiver.  
     
     
         155 . The receiver of  claim 154 , wherein the receiver is a personal computer and the user activity comprises keystrokes on a keyboard input device  
     
     
         156 . The receiver of  claim 154 , wherein the receiver is a personal computer and the user activity comprises clicks on a mouse input device.  
     
     
         157 . The receiver of  claim 156 , wherein the user activity further comprises keystrokes on a keyboard input device  
     
     
         158 . The receiver of  claim 151 , further comprising means for soliciting a user to specify when content should be received and wherein the receiving means receives content based on the user specifications  
     
     
         159 . The receiver of  claim 159 , wherein the user specifications include time of day when content should be received.  
     
     
         160 . The receiver of  claim 158 , wherein the content comprises base packages and delta packages and the user specifications includes a first time period when base packages can be received and a second time period when delta packages can be received.  
     
     
         161 . The receiver of  claim 151 , further comprising means for suspending reception of content when the monitoring means determines that reception will interfere with other receiver activity  
     
     
         162 . The receiver of  claim 161 , further comprising means for automatically enabling reception of content after the monitoring means determines that reception will not interfere with other receiver activity.  
     
     
         163 . The receiver of  claim 161 , further comprising means for automatically enabling reception at a time of day when reception will most likely not interfere with other receiver activity.  
     
     
         164  The receiver of  claim 161 , wherein the monitoring means determines that reception will not interfere with other activity by monitoring user activity on an input device of the receiver.  
     
     
         165 . The receiver of  claim 164 , wherein the receiver is a personal computer and the user activity comprises clicks on a mouse input device  
     
     
         166 . A receiver in a multicast system, comprising 
 a package receiver for receiving packets containing URL data items from a multicast network and assembling the received packets into a channel, wherein the channel comprises a set of URL data items;    a memory for storing the channel, and    a content viewer for allowing a user to request access to and access the URL data items in the stored channel    
     
     
         167 . The receiver of  claim 166 , further comprising a browser for searching the memory for URL data items requested by the user.  
     
     
         168 . The receiver of  claim 166 , wherein the receiver comprises a personal computer.  
     
     
         169 . The receiver of  claim 166 , wherein the receiver comprises a set top box.  
     
     
         170 . The receiver of  claim 166 , wherein the receiver is integrated with a digital television.  
     
     
         171 . The receiver of  claim 166 , wherein the packets received from the multicast network are encrypted and the package receiver decrypts the packets.  
     
     
         172 . A system for multicasting URL data items from web sites to a plurality of receivers, comprising: 
 a web crawler for retrieving URL data items from the web sites and formatting the retrieved URL data items into packages;    a package delivery subsystem for receiving the packages from the web crawler, fragmenting the packages into packets and transmitting the packets to a multicast network; and    a conditional access system for determining which receivers are authorized to receive the packets, wherein the multicast network multicasts the packets only to authorized receivers.    
     
     
         173 . The system of  claim 172 , wherein the web crawler retrieves URL data items from the web sites according to a predetermined channel definition.  
     
     
         174 . The system of  claim 172 , wherein the multicast network multicasts an electronic program guide to each receiver, and wherein the electronic program guide contains descriptions of the web sites from which URL data items were retrieved.  
     
     
         175  The system of  claim 174 , wherein a receiver uses the electronic program guide to subscribe to selected web sites and the system further comprises a registration server for tracking subscription information.  
     
     
         176 . The system of  claim 175 , wherein the registration server provides the subscription information to the package delivery subsystem.  
     
     
         177 . The system of  claim 172 , further comprising a cache hit tracker which receives usage reports from the receivers, wherein the usage reports contain information identifying which URL data items, from the set of URL data items received by the receiver, were accessed by a user.  
     
     
         178 . The system of  claim 177 , wherein the cache hit tracker stores the usage reports in hit log files.  
     
     
         179 . The system of  claim 178 , wherein the cache hit tracker provides the hit log files to the web sites from which the URL data items were retrieved.  
     
     
         180 . The system of  claim 172 , wherein the multicast network multicasts the packets to the receiver over a one-way high speed link.  
     
     
         181 . The system of  claim 180 , wherein the high speed link comprises a satellite link.  
     
     
         182 . A system for multicasting content organized into channels to a plurality of receivers, wherein a channel's content includes a plurality of URL data items from at least one web site, comprising: 
 a web crawler for retrieving the URL data items from the web site via a TCP/IP network and formatting the retrieved URL data items into packages;    a package delivery subsystem for receiving the packages from the web crawler and fragmenting the packages into packets;    a conditional access system for determining which receivers are authorized to receive the packets; and    a multicast network for receiving the packets from the package delivery subsystem, wherein the conditional access system encrypts the packets and the multicast network multicasts the encrypted packets to the authorized receivers, and wherein the authorized receivers store the packets in a memory and decrypt the packets.    
     
     
         183 . The system of  claim 182 , wherein the web crawler compresses a subset of the retrieved URL data items, and wherein each URL data item is compressed individually independent of other URL content such that the receiver can decompress each URL data item without decompressing other URL data items  
     
     
         184 . The system of  claim 182 , wherein the web crawler assembles a base package containing each URL data item in the channel and subsequently assembles a delta package containing URL data items which have changed or are new since the previous assembling of the base package.  
     
     
         185 . The system of  claim 184 , wherein the web crawler assembles the base packages and delta packages according to a schedule.  
     
     
         186  The system of  claim 184 , wherein the multicast network multicasts the base packages and the delta packages according to a schedule.  
     
     
         187 . The system of  claim 186 , wherein the base packages are scheduled for multicasting at a time when the receiver is not likely to be in use for other applications  
     
     
         188 . The system of  claim 184 , wherein the web crawler compresses a subset of the retrieved URL data items, and wherein each URL data item is compressed individually independent of other URL content such that the receiver can decompress each URL data item without decompressing other URL data items.  
     
     
         189 . The system of  claim 188 , wherein the web crawler difference compresses a subset of the URL data items that are present in both the delta package and the previous base package  
     
     
         190 . The system of  claim 189 , wherein the web crawler performs difference compression by: 
 dividing a URL data item in the delta package into sections; and    for each section, places into a compressed version of the URL data item, one of a reference to where that section can be found in the base package, or the section of the URL data item from the delta package    
     
     
         191 . The system of  claim 184 , wherein the web crawler assembles a second delta package which contains URL data items which have changed since the assembling of the previous delta package.  
     
     
         192 . The system of  claim 182 , wherein each receiver comprises a content viewer for allowing a user to access the stored URL data items.  
     
     
         193 . The system of  claim 192 , further comprising a cache hit tracker which receives usage reports from the receivers, wherein the usage reports contain information identifying which URL data items, from the set of stored URL data items, was accessed by a user.  
     
     
         194 . The system of  claim 193 , wherein the cache hit tracker provides the usage reports to the web sites from which the accessed URL data items were retrieved.  
     
     
         195 . The system of  claim 182 , wherein the TCP/IP network comprises the Internet.  
     
     
         196 . The system of  claim 182 , wherein the multicast network multicasts the packets to the receiver over a one-way high speed link.